1. Field of the Invention
The present invention relates generally to the field of welding. More specifically, the present invention relates to methods and apparatus designed to increase welding productivity of a manufacturing shop.
2. Related Art
The metal fabrication industry has been around for many years. After the first World War, the shielded metal arc process became very popular through the use of extrusion technology. For continuous operations, such a process was not useful. As a result, semiautomatic welding processes using continuous wire were developed in the 1960s to improve productivity. In the early 1970s, arc welding was a hot and dirty operation, using principally large diameter continuous consumable wires. As the technology to draw continuous consumable wire to smaller diameter became available in the early 1980s, the arc welding industry started using continuous consumable wire diameters as small as 0.030 inch for continuous welding. Today, both cored arc welding wires and solid arc welding wires are available in a range of diameter starting at 0.025 all the way to 0.25 inch for continuous welding. With the advent of robotic technology, the continuous consumable wires can be supplied in bulk packs with torsionless delivery, with individual weights of 1,000 pounds.
In spite of this evolution in the supply of continuous consumable wire, the average welding amperages used in the arc welding industry have substantially dropped due to availability of lower diameter continuous consumable wire sizes. Welding deposition rates are related to the welding amperage used. As a result of the decreased amperage, the welding deposition rates have also substantially reduced.
In order to increase the arc welding productivity of a manufacturing shop, it is often desirable to measure two (2) key parameters. First, it is desirable to establish the average amperages used during arc welding, which relate to the pounds deposited per hour at 100% arc efficiency. Second, it would be desirable to measure the efficiency of the welding arc at the point of use. The arc welding efficiency, in other words, could be described as the ratio of the time the welder spends actually arc welding divided by the welder's total time performing arc welding and related processes during the welder's work day (the sum of "time performing arc welding` and "time for related processes" is referred to as "total elapsed time" for simplicity herein). These related processes typically include setting the welding machine and accessories correctly, positioning himself so that he can appropriately weld in the most comfortable position, time spend changing electrodes, wires, taps, gas bottles, and other activities such as placing the grounds, waiting for cranes or cleaning. Time spent for coffee, lunch and other qualified absences are deducted and not included in total elapsed time.
Most arc welding management systems do not objectively measure the duty cycle experienced by the overall welding operation at the manufacturing plant. This is due to the unavailability of a suitable device and method that can be used without interrupting the manufacturing cycle, which would measure effectively the average amperage and the welding efficiency at the selected work station. Further, such a device should be affordable so that a number of such devices can be deployed in a manufacturing plant to generate meaningful evaluation of the overall arc welding productivity over a 24-hour period or more.